There’s only really so many ways to verify the age of someone that you’ve never seen (actually, it often isn’t all that much easier in person, but that’s another story).

You can treat them as if they’re of-age if they have a credit card, but that’s inaccurate and a violation of credit-card merchant agreements (symptoms include suddenly having to change payment providers).

You can match identification document information against an identification provider like Aristotle-Integrity, but that’s unreliable and fraught with issues, and doesn’t prove that the information describes the applicant.

There must be a simpler way to verify Second Life accounts as adults! Oh, wait…. here it is!